/*
 *  CGPointUtils.c
 *  PinchMe
 *
 *  Created by Jeff LaMarche on 8/2/08.
 *  Copyright 2008 __MyCompanyName__. All rights reserved.
 *
 */

#include "CGPointUtils.h"
#include <math.h>

#define pi 3.14159265358979323846
#define degreesToRadian(x) (pi * x / 180.0)
#define radiansToDegrees(x) (180.0 * x / pi)

//拐点
CGFloat distanceBetweenPoints (CGPoint first, CGPoint second) {
	CGFloat deltaX = second.x - first.x;
	CGFloat deltaY = second.y - first.y;
	return sqrt(deltaX*deltaX + deltaY*deltaY );
};
CGFloat angleBetweenPoints(CGPoint first, CGPoint second) {
	CGFloat height = second.y - first.y;
	CGFloat width = first.x - second.x;
	CGFloat rads = atan(height/width);
	return radiansToDegrees(rads);
	//degs = degrees(atan((top - bottom)/(right - left)))
}
CGFloat angleBetweenLines(CGPoint line1Start, CGPoint line1End, CGPoint line2Start, CGPoint line2End) {
	
	CGFloat a = line1End.x - line1Start.x;
	CGFloat b = line1End.y - line1Start.y;
	CGFloat c = line2End.x - line2Start.x;
	CGFloat d = line2End.y - line2Start.y;
	
	CGFloat rads = acos(((a*c) + (b*d)) / ((sqrt(a*a + b*b)) * (sqrt(c*c + d*d))));
	
	return radiansToDegrees(rads);
	
}




